Stud Material

[christianroth]

Sorry about the basic question, but we have ran into situation for a particular project were we need to turn a custom stud.

The stud will be 5/16" in diameter and will need to be torqued to 18 ftlbs.

The threads will be cut to M8x1.25x15mm on either side. The total lenght of the stud is 201mm.

Being that the stud is so long and the torque needed I would expect basic mild steel would be out of the question.

What material recommendation would you have?

As well when the stud threads bottom is it advisable to have a shoulder as to elimante the threads from binding into each other?

 

[SnTMan]

From the information you give, if I've done my arithmetic correctly, and using a handbook nut factor, you are going to develop about 60 ksi stress in your stud, just from the applied torque. Your stud will probably need to be something like low alloy, quench and temper material, such as Gr 5, 4140, etc.

The length is not really an issue if you have enough threaded length such that the nut does not run out of threads during tightening.

Not sure what your second question is referring to, bottoming the stud in a threaded hole, bottoming a nut against the thread runout, but if the latter, I would provide enough thread length to prevent it. If the former, maybe no harm in it.

Regards,

Mike

 

[christianroth]

Thanks for the help, what are grade 5 bolts typically made of?

The second question I had was that the studs do not bottom out, as the hole is thru. I was concern with tightening the stud until the threads run out or bind into the hole threads. I've seen some circumstances where a shoulder is machined after threads to distribute the load evenly.

 

[EdStainless]

As long as you have a few threads (5 or 6) engaged they will be loaded fine.
Gr5 are usually alloys steels, 4130 and 4140 being common. These are heat treated with a quench and temper.

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[christianroth]

EdStainless, I was more concerned with the end of the male threads binding into the start of the female threads at the bottom of the stud.

 

[NickE]

A shoulder would probably be ideal, however most studs ive used, automotive/motorcycle, dont have one.

 

[christianroth]

So I've contact every metal supplier within 200 miles, no one carries 4140 that small. The best material suggested would be 1144, upon reading up on it it seems that it may be to be brittle.

 

[TVP]

SAE 1144 is not a proper stud/fastener grade. The diameter that you need is produced by cold drawing wire rod into wire, which is the normal input for cold heading of fasteners. Since you need a small quantity, you are initially limited to steel in the bar product form. Either purchase 4140 in the larger size, or try contacting cold heading wire suppliers to see if you can purchase a small quantity of smaller wire. CHQ wire suppliers in the USA include Republic Steel, Charter Wire, Johnstown Wire, and Walker Wire (Mittal Steel).

 

[SnTMan]

Maybe try a bolt manufacturer?

Regards,

Mike

 

[CoryPad]

Grade 5 requires a carbon concentration of 0.28 to 0.55 mass percent. This means SAE 1030, 1035, 1040, 1045, and 1050 can be used.

Regards,

Cory

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[btrueblood]

Check McMaster Carr, they carry 4140 rod in 1/4" and 3/8" diameters, as well as precision-ground 5/16" diameter.

 

[christianroth]

Found some at Frys steel, thanks.

Any idea what 1144 would be used for?

 

[CoryPad]

Screw machined parts for non-fatigue critical applications.

Regards,

Cory

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